To study the effects of variable temperature (VT) on magnitude of ΔδR/S of rac-5a.
| Entry | Temp. (°C) | Chemical shift difference (ΔδR/S)b (ppm) | |
|---|---|---|---|
| CH̲1 | CH̲2 | ||
| 1 | −50 | 0.52 | 0.15 |
| 2 | −40 | 0.40 | 0.11 |
| 3 | −20 | 0.19 | 0.05 |
| 4 | −10 | 0.14 | No resol. |
| 5 | 0 | 0.11 | No resol. |
| 6 | 10 | 0.09 | No resol. |
| 7 | 25 | 0.06 | No resol. |
a
In NMR tube, the CSA (S)-3a (0.1 mmol) and rac-5 (0.05 mmol) were dissolved in chloroform-d (0.6 mL) and after shaking the NMR tube for 30 seconds, 1H-NMR spectrum was recorded on a 400 MHz NMR spectrometer at variable temperatures.
b
Calculated from the 1H-NMR spectrum.